The three inches of height and nearly 50 pounds of weight that separate Buffalo Bills defensive end Mario Williams and draft prospect Khalil Mack make a comparison between the two seem like a stretch to most.

But Cleveland Browns coach Mike Pettine has coached one and studied the other. He's seen enough to liken Williams, the former No. 1 overall pick of the Houston Texans, to the University of Buffalo linebacker who just might be the choice for the Browns with the No. 4 overall pick in the 2014 NFL Draft.

"When you have a guy that's a special player like that, not that he's played the same position as Mario, but what we did with Mario in Buffalo, he didn't line as up as the left defensive end all the time," Pettine said, according to buffalo news.com. "He was on the left. He was on the right. He was standing up. He was inside as the three. He was on the nose sometimes. We actually stood him up a couple times."